Spark-plug



e. L.ITRUESDELL.

SPARK PLUG.

APPLICATION FILED SEPT. 23' I918.

1,339,429. Patented May 11,1920.

@uvawtoz GL 7m esdell.

GEORGE rnnnsnnnn, or nnnwoon FALLS, MINNESOTA.

SPARK-PLUG.

Application filed September 23, 1918:

To. all whom it may 0012mm:

Be it known that I, Gnonon L. TnUnsonLL, a citizen of the United States, residing at Redwood Falls, in the county of Redwood, State of Minnesota, have invented certain new and useful Improvements in Spark- Plugs; and I do hereby declare the follow.- ing. to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to'which it appertainsto make. and use the same.

Theinvention relates to an igniting device foiyinternal combustion engines, and moreparticularly to the class of. spark plugs embodying improvements. over the subject; matter of Letters Patent No. 1,263,005,"is.- suedto me onor about April 16th, 1918.

The primary object of the invention isto generally improve the. spark plugs of the indicated character, and to the end that efficiency may be promoted aswellas simplicity in construction and convenience of adjustment and control.

The invention will be particularly eX- plained in the specific description followmg In the accompanying drawing 2- Figure 1, is a vertical sectional elevation of the improved spark plug, constructed in accordance with the invention.

Fig. 2, is a sectional view taken through the stem.

Fig. 8, is a sectional the eye and pin.

Referring more particularly to the drawing, A, designates generally an iron shell having a removable diamagnetic end head 5 formed with a central neck 6 constituting the stem of the spark plug. The head 5 is formed with a cavity 7, while fitted within the shell or casing A is an electro-magnetie coil 8 wound around an iron core 9, the latter being secured to the closed end of the shell or casing A through the medium of a screw 10 engaged in said end and core, while arranged within the cavity 7 is a disk shaped armature 11,,the cavity 7 being of sufiicient depth to permit vertical movement of the armature under the influence of the electro-magnet within the shell or casing A. The head 5 has supported therein a diaphragm 12 separating the interior of the shell or casing from the cavity 7, the dia phragm 12 being held in place by the engagement of the shell or easing A, in the view taken through Specification of Letters Patent.

' ture 11. at its inner; end,

Patented May 11, 1920.

Serial No. 255,323.

head 5,as. is clearly shown in Fig. 1, of the drawing.

The stem (3. is formed with an outer tapered end 1% wh1le centrally of said stem is. a bore or passage 15 opening into the.

cavity 7. at its inner end, while the outer end opens into a socket 16 which latter. opens through the smaller end of the stem. Workingiwithin the bore or passage 15 is a rod or shank 17 which is connected to the armaendis formed a flat eye 18, the eye 18 being fitted within a notch or recess 19 formed in the inner end of a movable contact 20, working. within said socket. The eye is loosely connected to the contact 20 through the medium of a cross pin 28 mounted transverselyin the contact 20 and intersecting the recess 19' to passthrough the eye 18.

Located: within the socket 16 and surrounding. the rod or shank 17 is a coiled expansion. spring 24: which bears upon the contact 20 to move the same outwardly.

Removably fitted over the tapered end 1 of the stem 6 is athimble plug 25 which is formed with a wrench engaging enlarged upper end, having screwed therein a locking nut 27 which works against a flange nut 27 on the stem 6, and in this manner the thimble plug is detachable. The outer end portion of the plug is internally tapered correspondingly to the tapered end 14 of the stem, while eXteriorly of said plug on the outer end portion are screw. threads 29 for the detachable mounting of said plug in the usual plug opening in the head of a cylinder of an internal combustion engine.

Formed at the outer end of the thimble 25 is a downwardly arched flat bridge having a stationary contact 30 disposed opposite the contact 20 to be engaged normally thereby.

The stem 6 is insulated from the plug 25 through the medium of mica or other insulation 32 interposed between the tapered end portion 14: of said stem, and the internally tapered end portion of said thimble. l 1

The rod or shank 17 below the armature 11 within and the cavity 7 is provided with while at the outer a collar 33 which is rigid thereon and has to normally hold the armature 11 in lowered position so that the eye will have its inner end contacting with the pin 23 in the movable contact 20 until the armature is raised, whereupon the outer end of the eye 18 engages the pin 23 for the lifting of the contact 20 against the resistance of the spring 24: and thus the spark plug when operating will have the contacts normally engaged with each other.

Through the closed end of the shell or casing A is passed an electric lead wire 35 which preferably enters through the shell or casing A and serves to connect with the free end of the coil of the ignition system, the circuit being completed through the spark plug as in the ordinary spark plug.

The contact 20 rests normally upon the contact 30 so that a current impulse entering over the line 35 passes through the winding 8 and thence by way of the diaphragm 12, the head 5, stem (3,vmovable contact 20, fixed contact 30 and thimble to the cylinder of the engine from which it passes back to its source. This impulse magnetizes the core 9 which causes it to attract its armature 11 which through the medium of the rod 17 and pin 23, raises the contact 20 from the contact and strikes a spark. At the end of the impulse the core 9 is dema 'netized and the contact 20 is permitted to reengag'e the contact30 ready for the next operation, -It will thus be seen that however weak the current may be, a spark will be formed between the terminals or contacts 20 and 30 if the current has suflicient strength to energize the electro-magnet to a degree sufiicient to cause it to attract and move its armature 11.

What is claimed is:

In a spark plug, the combination with a stem having a bore enlarged at its inner end into a socket, a thimble around and insulated from the stem and having a bridge across its inner end, and a fixed contact carried by said bridge; of a m0vable contact slidably mounted in said socket and having a transverse notch a spring between the bottom of the socket and the contact urging the latter toward the fixed contact, a pin across said'notch, a rod extending through said bore and having an eye entering said notch and engaged by the pin, an armature connected with the upper end of the rod, and an electro-magnet carried by the stem and adapted to act on said armature.

In testimony whereof I affix my signature in the presence of two witnesses.

GEORGE L. TRUESDELL. lVitnesses:

J. K. DRURY, F. A. GRAY. 

